The overall objective of this Program is to evaluate broadly the mechaniss of arterial pressure regulation in normal and hypertensive states. Two major areas of study are emphasized: first, the regulation of body fluid volumes and electrolytes; second, the regulation of vascular smooth muscle tone and systemic vascular resistance. The Program integrates many levels of biological function ranging from cellular events to integrative mechanisms of the whole organism that ultimately determine arterial pressure. The conceptual framework of the Program has evolved from utilization of mathematical analysis (computer systems analysis) to evaluate the complex interactions of cardiovascular function.